One of the currently popular forms of optical retrieval apparatus uses an optical recordable element in the compact disc or CD. Digital information is stored in the form of low reflectivity marks or pits on an otherwise reflective background. In this format, the optical information is most often in the form of read only memory or ROM. Optical information is not usually recorded in real time but rather is produced by press molding. In a typical process, the optical recording substrate is first press molded with a master containing the digital information to be reproduced. The thus formed information is then overcoated with a reflective layer and then with an optional protective layer. In those areas having the deformations or pits, the reflectivity is lower than in those areas not having the deformations.
It is desirable to produce optical recording elements which, when recorded in real time, produces a record that mimics the conventional CD on read out. In this manner, information can be added to the CD and the CD can be used on a conventional CD player.
One recently disclosed optical retrieval apparatus of this type is the so called photo"Photo CD". In this system, conventional photographic film is first processed in a conventional manner. Then, the images from the film are digitized and the digital information is recorded in a CD readable form on an optical recording material. Images can then be played back on a conventional CD type player into a conventional television. Since a CD has a capacity for a number of digitized images that is greater than the typical roll of consumer film, it is anticipated that the user will want to add images and information to a partially recorded CD. Thus there exists the need for recordable, CD compatible optical recording material.
One method for forming a recordable element that mimics conventional mold pressed CD elements is to provide a transparent heat deformable support having thereon, in order, a layer of a dye that absorbs recording radiation and a reflective layer. Exposure of the recording layer through the support by the recording beam heats the recording layer to an extent that it is said that the surface of the heat deformable support just adjacent to the recording layer surface is deformed. Materials of this type are described in U.S. Pat. No. 4,940,618, European Patent Application 0353393 and Canadian Patent 2,005,520. There are a number of problems with using a deformable support including the cost of producing the optical element.